Automatic telephone system



Junezs, 1929. F. ALDENDORFF I 1,118,449

l l AUTOMATIC TELEPHONE SYSTEI original Filed Jan. 12, 1925 ,4SheetS-Sheet 1 June 25, 1929.` F. ALDENDoRFF AUTOMATIC TELEPHONE sYs'ml 4 Sheets-Sheet 2 Original, Filed Jan. 12, 1925 WNW,

E ALDENDORFF 1,718,445 1 AUTOMATIC TELEPHONE SYSTEM June 2.5, 1929.

Original Filed Jan, 12, 1925 4 Sheets-Sheet com June 25, 1929. F. ALDENDORFF 1.7183149 AUTOMATIC TELEPHONE SYSTEI origina; Filed Jan. 12,. 1925 4 sheets-sheet 4 m f QQ?? Cil Patented June' 25, 1929.

UNITED STATES PATENT OFFICE.

FRTZ A.LTE-NDORFF, OF BERLIN, GERMANY; CHARLOTTE ALDENDORFF, HEIRESS OF .SAID FRITZ ALDENDORFF, DECEASED.

AUTOMATIC TELEPHONE SYSTEM.

Original application filed January 12, 1925, Serial No. 1,889, and in Germany, January 14, 1924. Divided and this application filed August 4, 1927.

This application is a division of patent application Serial No. 1889 of January 12, 1925 and describes an invention which relates to telephone systems operating with selectors and its object is to provide devices by which wrong connections arising from the fact that the line finders, group selectors etc. operate too slowly to respond to very quick movements of the switch cont-rollers, are obviated.

A feature of the invention is a registerless, power-driven switching or telephone system in which no revcrtive impulses sent back from the switches to the s 'itch controlling point are required.

The invention is illustrated in the drawing in which 1 shows a constructional form of the selector and 1a shows a part of a selector whose irush carrier may be moved longitudinally and rotated.

Fig. 1" shows the longitudinal movement controlling mechanism of the switch of Fig. 1a.

Fig. 2 shows a circuit arrangement for the selector when used as a line finder.

Fig. 3 shows circuits of a selector with longitudinally movable and rotarj.v7 brush shaft.

i Fig. S illustrates circuits of a group selector whose brushes execute rotarj.v movements only.

Fig. i shows circuits of connector that executes rotarv movements only.

Fig'. 5 shows a circuit in which the. quick stopping effect of the stopping' magnet is obtained by inserting a resistance in its energizing circuit.

Fi g. 6 shows a circuit in which the quickstopping effect of the stopping magnet arma ture is attained by counteracting ampere turns.

Fig'. 7 illustrates a form of the selector' in which. instead of two toothed wheels as in Fig. 1 onlv one toothed wheel is employed.

F' 8 is a diagrammatic remt-sentation of one form of contact bank in which the designating contacts are displaced with respect to the conversational contacts.

Selectors whose circuits are arranged as shown in Figs. 2. 3a and Ll may, on the whole, be built in the manner illustrated in Fig. 1 except that a cam dish 300. Fig. 3 or i-90, Fig. 4; which is not provided in Fig. 1, is com- Serial No. 210,698.

with a spring box 9. The spring box 9 has an i upwardly extending' hub 11 and a downwardly extending hub 12 that rests on a bushing 13 fixed to the shaft 1. One end of the spring 14 of the spring box is connected to t-he bush ing 13 and its other end is attached to the periphery of the spring box 9. TVhen current impulses are sent through the magnet 15 the spring box 9 is rotated in the direction of the arrow 16, a holding pawl (not shown) being provided which prevents backward rotation of the spring box 9. Vhen the spring box 9 is wound up the wheel 17 is held against movement by the pawl 18 of a magnet 19 so that the shaft 1 with the brushes 2, 3, 4, 5 is also prevented from rotating. Mounted on the wheel 17 are two slip rings 20 to which current is conducted by two brushes 21, 22. The two slip rings are interconnected by a Contact that .is carried round with the wheel 17 when this wheel moved out of its normal rotary position with respect to the spring box 9. But as soon as the wheel 10 occupies a certain position with respect to the wheel 17 a pin 24 of the wheel 10 rai es a pin 23 and thus opens the contact; that interconnects the ring 20. This contact or switch is designated in Fig. 2. The spring 14, when it is wound up, tends to turn the brush carrier 1 with its wheel 17 in the direction of the arrow 26 and it executes aturn in this direction when the starting and stopping magnet 19 is energized.

In a selector' with a longitudinally movable shaft 1', Fig. 1, a toothed wheel 17 corresponding to the wheel 17, Fig. 1, and a spring box 9 corresponding to the spring box 9, Fig. 1, and having a circle of teeth 10, is provided. The toothed wheel .17 however has a hollow hub 7 upon which the spring box 9 is adapted to rotate. The shaft 1 extends downwardly through the spring box and has a series of circular teeth 27 with which the pawl of a lifting .magnet 28 may engage. The shaft 1 has a groove 29 into which a pin 30 arranged in the box of the wheel 17 protrudes, so that the shaft 1 may move length- For Wise in the wheel 17 but cannot turn therein. By the lifting magnet 28 the shaft 1 may be lifted step-by-step and When the Wheel 17 is then released by a magnet corresponding to magnet 19, Fig. 1, the shaft is rotated by the spring 144 of the spring box until it is stopped in the manner hereinafter described. The shaft 1 is restored to its normal position by its being turned until a pin 31 of the same strikes against a slide Way in the term et a long stop 32. lVhen the shaft is in this position a holding' pawl 38, Fig. 1b, Will register With a groove 34 in the shaft so that the latter drops down. lVlien the pin 31 has fallen beneath the slide Way 32 the spring turns the shaft a little t'urther round until the pin 81 is restored to the position shown in Fig. l"L and the holding paWl 201, Fig. 8, engages with the wheel 17 and holds it and the brush carrier in the normal position indicated in Fig. 3.

By placing Figs. 2, 8 and 4 side by side a complete circuit arrangement tor an eX- change with line finders, Fig. 2, group selectors, F ig. 3 and connectors, Fig. 4, is obtained.

It it Will now be assumed that a subscriber S, Fig. 2, desires to establish a connection with the line 224. When the subscriber S raises his receiver a current flows from the positive pole through the line'relay 40, contact 41, substation S, contact 42 of the cutotf rela-y 43 to the negative pole. The line relay 40 closes its contacts 44. 45 and opens contacts 46, 47. The opening of the contacts 46, 47 results in the positive pole being disconnected trom the designating contacts 48-r 49. By the closure ot' the contact 45 the cut-oit' relay 43 is connected to the test wire 50 and test contact 51 of the calling subscriber. At contact 44 a circuit is closed which extends troni the positive pole through the starting relay 51 ot the line finder 52. rl`he relay 51 sends a current from the positive pole through its contact 53. brush 54 oi the trunk finder, contact 55 ot relay 56. starting magnet 19 to the negative pole. The starting magnet 19 pulls its stopping pawl 57 away troni the Wheel 17 and this latter is now turned. at a high speed by the spring 14, F 1. lVhen the Wheel 17 with the brushes 58, 59. 60, 61 is moved out ot' its normal position the oit-normal switch 25 is closed andl the relay 56 is energized. The starting magnet 19 is then maintained energized by a current that flows through the contact 62 of the relay 64, Wiper 58 and the designating bank conta-cts 65 that are-connected to the positive pole of the battery. The magnet 19 remains energized until the brush 58 reaches the bank contact 49. The armature 57 then retracts and stops the Wheel 17 so that the Wipers 59` 69. 61 are held on the contacts 66, 67. 68. It magnet 19 does not operate tast enough it could happen that the brush .58 oversteps the contact 49 and only stops on the next contact 48 from which the positive pole is also disconnected by the contact 47. ln any case, ii' necessary as many contacts 48, 49 are disconnected from the positive pole as are necessary to prevent the brush 58 from flying past the last bank contact that is disconnected from the positive'pole7 Which might happen it the armature 57 acts too slowly. rl`he calling line is always the one that corresponds to the last contact 48 that is disconnected from the positive pole. lVhen the brushes are stopped on the Iirst contact 49 disconnected trom the positive pole the magnet 19, as soon as its armature 69 falls back, receives a current impulse that flows through contact 69, 79, 71, 63 to the negative pole. The armature 57 thus again attracted and allows the toothed Wheel 17 to turn through an angle corresponding to a further tooth in the direction of the arrow, because, in consequence of the interruption at 69 and of the disconnection oi' the positive pole troni the contact 48, the armature 57 immediately drops back again and again stops the Wheel 17. The test brush 58 Will now be resting on the bank contact 51 which is connected through the cut-ott relay 43 to the negative pole. Hence the relay 72 Will be energized by a current flowing from the positive pole through 5S, 72, 59, 51, 45, 43 vto the negative pole. rhe selt-interrupter 69 is switched oit at 70 so that the arn'iature 57 of the magnet 59 rcmains still. 1t is to be noted'that the magnet 19 is made to allowT its armature 57 to drop bach extremely quickly by a condenser 7?). The relay 72 closes its contact 73 and thus renders the calling line engaged so that further relays like 72 -or test relays in the connectors cannot be energized when the brushes ot other selectors are stopped on the bank contacts et the calling line.. Yl`he liuc relay 72 by its contacts 74 75 also connects the calling line through to the group selector. Fig. il. so that the impulse. relay 262 ot' the group selector is energized. Furthermore the relay 72 by its contact 76 opens the circuit of the rewinding magnet 15 which would otherwise be closed when the release relay 293 and the relay 64 are energized. The calling subscriber new sends in a series ot two impulses, i. e. he causes tivo interruptions ot' his loop to take place in rapid succession so that the'armatures 294, 205 drop la f twice and two impulses flow from the negative pole through Contact 206 Which was closed due to a current from the negative pole 204, 20S, 207 to the positive pole) When the relay 202 Was first energized, contact 298. contact 209, lifting magnet 28 to the positive pole. Vllheli't'ting magnet 28 now raises the shait 1. Fig. 1, with the brushes 210, 211. 212. 218 step-by-step until they reach the seor ond level ot the contact bank.- rllhe calling` subscriber having novv sent in his tvfo hunllt) drcd impulses`r the armatures 204, 205 now remain attracted Jor a relatively long interval so that the relay 214 which was energized through 206, 214, 215 is kept short-circuited at contact 216 until its armature drops back and the contact 217 is closed. As the vertical ott-normal switch 218 was closed at the lirst vertical step ot' the shaft the starting magnet 219 now receives a current which flows trom the negative pole through 220, 218, 217, oli'- normal switch 221', 229 to the positive pole. The wheel 17 and the shaft 1 with the brushes 210-213 is now released for rotary movement so that the spring 14 whirls the brushes round until the magnet 219 which is bridged by a condenser' 222 and receives current during rotation of the brushes through the contact 223, brush 213 and bank contacts, such as connected to the negative pole, is deenergized. This dcenergization takes place as soon as the brush 213 reaches a contact 224 whose wire 225 is disconnected from the negative pole, this wire leading to a tree connector. Fig. 4. The stopping pawl 207 engages with the wheel 17 and arrests the brushes 211` 212., 213 on wires leading to the connector, Fig. 4. In the group selector, Fig. 3. the relay 226 is now energized by acurrent that Hows Jfrom the negative pole through 220, retracted armature 227 ot' the magnet 2.19, 226, brush 212. wire 228` resistance 401, ott-normal contact 402 of the connector to the positive pole. The relay 226 opens the contacts 229, 230. 231 and at the same time eX- tends the voice current wires through the wipers 210, 211 to the impulse relay 402 ot' the connector. The impulse relay 202 ot the group selector is disconnected at contacts 23 231. This does not however result in the restoration ot the group selector because the short circuit around the release relay 203 is kept open at contact 229. The calling subscriber now sends in two tens impulses. (ln the tirst retraction ot the armature ot the im pulse relay 402 a current impulse Hows from the negative pole through contact 406, 407, 408, wire 409` bank contact 410. wiper 414, Contact 415 and through the magnet 4'19 bridged b v the condenser 420. The magnet 419 pulls the holding pawl 418 away from the toothed wheel 417 so that this wheel with the brushes A.111414 is rotated. The brush 414 leaves the contact 410 but is immediately reconnected to negative potential by a long contact 421 so that the magnet 419 remains energized until the brush 410 reaches the contact 422, which in the meantime will have been disconnected from the negative pole by the reenergization of the impulse relay 402. The magnet 419 thus allows the stopping pawl 418 to reen with the wheel 417 so to stop the brushes 411. 414 on the setot bank contacts corresponding to the contact 422, lVhen the second tens impulse atlects the relay 402 the brushes 411-414 execute a further long step corresponding to their movement from 410 to 422 so that they now reach the contact 423. It is to be noted that the spring which turns the brushes 411-414 is wound in such a way that the long steps ot the brushes keep pace with the numerical impulses from the subscriber. During the interval after the series ot ten impulses have been sent in the changeover relay 424, which was energized by a current from the negative pole through 406, 422, 425 to the positive pole is deenergized by the short circuit closed at 426 so that the relay 427 is energized by a current that flows from the negative pole through 429, off-normal contact 413, left hand win ding et' 427 to the posit-ive pole. The

impulse wire 431 is connected by the relay 427 and thrbugh contact 421 to an interrupter 433 controlled by a cam disk 400, and through this interruptor and a contact 434 it extends to the toothed wheel controlling-magnet 419. When the calling subscriber now sends in his series of unit impulses the magnet 419 is energized at each impulse by a current that tiows from the negative pole through 406, 407, 432, 433, 434, 419 to the positive pole. lhenever` during such an impulse, a tooth of the cam disk leaves the interrupter 433, this latter is opened so that the pawl 418 reengages with the toothed wheel 417 and again stops the brushes 411-414 until the next tooth ot the cam disk reeloses the interrupter 433 and another current impulse flows from the negative pole through 406, 407, 432, etc., and through the magnet 419. Thus, when two unit impulses are sent in the toothed wheel 417 is released twice so that the brushes 411 414 are caused to execute two short steps.

The brushes are new set onto the line et' No. and the impulse relay 402 is maintained energized so that the change-over relay 424 again lets its armature drop back and thereby connects the negative pole through 429, armature contact 435, to the test relay 43o for the testing operation. It is to be noted here that the relay 437 was energized by the relay 424 after the energization of relay 437. The energizing circuit of the relay 437 extends from the negative pole through 428, 438. 439, right hand winding ot relay 437 to the positive pole. By its encrgization the relay 437 was caused to close the contact 435 and the contact 440 of its locking winding.

lt will be assumed that the desired subscriber is free. This being the case the test re lay 436 is energized so that it closes its contacts 441, 442, 443, 444. At contact 443 a circuit is closed for an intermittent current through the ringing relay 445, this current flowing from the positive pole through the interrupter 446, relay 445, contact 447, contact 443 to the negative pole. At each attraction of the armature of the ringing relay the ringing current generator 448 is Connected to iii the wanted line through the contacts 441. lVhen the called subscriber responds the rclay 449 is energized and the ringing relay 445 is thus disconnected at contact 447. A t the same time a back release relay 451 is energized through Contact 450, this relay closing a lockingcircuit for itself at its contact 452. llVhen the called subscriber replaces his receiver the release relay 403 is deenergized by the negative pole being directly connected through 454, 455, to the resistance 456. lt the calling subscriber' replaces his receiver first the negative pole is directly connected to the resistance 456 through 406 and contact 457. TheV release relay 403 is thus short-circuited so that it closes its contact 45,8 and connects the interrupter 459 through 458, 460 of the oiinormal switch to the rewinding magnet 415. At the same time the negative pole is connected throughcontact 463, olli-normal contact 464 to the magnet 419 so that this magnet withdraws the pawl 418 from the Wheel 417 and holds it in this position until the oil-normal sivitch 464 is opened by the brushes 411e414 reaching' their normal position in which they are shown in the drawing, and the magnet 419 rcleases the payvl 418 so as to stop the brushes, The oit-normal switch 465 keeps the contact 460 closed until the reivinding magnet 415 has completely reivound the spring box of the selector, at which moment the circuit of the reivinding magnet is opened. llThen the release relay 403 is deenergized it also opens the contact 466 which results in the deenergization ot the relay 226 in the group selector, Fig. 3. II. the calling subscriber should not have replaced his receiver, the Wipers of the group selector Will .remain on the trunk leading to the connector, Fig. 4. This can be avoided by an auxiliary relay in the group selector. l"Vhcn the calling` subscriber hangs up, the impulse relay 262 drops back andthe release relay 203 is deenergized so that the circuit ot the magnet 219 is closed at contact 250, this circuit st. uding trom the negative pole through 250, oil-normal contact 251. 219 to the positive pole the magnet 219 pulls the pawl 201 out otl the toothed Wheel 17 and the spring 14, Fig. 1, new rotates the brushes and the shait 1 until the pin 31 strikes the guide Way 32 and the holding pawl 33. Fig. lh. enters the grom'e 34 oi the shaft. The shaft then drops down until the pin 31 leaves the guide way 32. rl`he springl 14 now turns the shaft a little further around until the oil-normal contact 251 is opened and the magnet 219 releases the .holding` paWl 201 and this latter finally yarrests the toothed Wheel 17. In the meantime the spring boxis reivound receives current through the interrupter 261, contactV 260, 215', contact 262 et.'v the onormal switch to the positive pele. l

when the spring box is reu'ound the olii-normal switch is thrown into its normal position and by the rewinding magnet 215 which Y the circuit of the rcwindinj,;l n'iagnct 215 is opened at contact 262. By the dcenergization of the release relay 203 the restoration of the line finder, Fig. 2, is initiated. llhen the Contact 263 is opened the circuit of the relay 72 is interrupted so that this relay allows its armature to drop back and close the circuit o'l' the restoring maejnet 15 at contact 76. The rewinding magnet i is energized by a current which flows from the negative pole through the interrupter 80, contact 81, 15, contact 76, contact 83 et the relay 56 to the positive pole or earth. The ren'inding` magnet noiv ope 'ates until the off-normal contact 51 is interrupted and the relay 56 deenergized. @n the deencrgization et the relay 56, which only takes place vrhen the spring 14, Fig. 1, is 'fully reivound the circuit ot the reiviuding magnet 15 is opened at contact 83. ln cases in which a calling subscriber S places his receiver, Without the brushes 58, 59, 60, 61 having reached his bank contact set, the relay 64 is energized by a current that flows from the positive pole through 85. 86, 8T, lett Winding or" 64 to the negative pole. The relay 64 then closes its contact 81 and thus closes the atoredescribed circuit (negative pole, 81, 15. 76, 83, earth) ot the rewinding magnet. The reivinding magnet then op crates until the spring box is fully reivound. As soon as a line finder is taken into use the trunk iinder 52 is caused to place its iv' 87, 54, 86 onto another trunk; for as the brush 87 encounters engaged tthe stepping magnet 8T receives iingu which flow from the negative pole through the interrupter 89, contact 90, Vmagnet 88, brush 87, contact 83 to the positive pole. The brushes oi the trunk finder are thus stepped oru'aro until they reach a trunk Whose associated contact 83 is open.

ln Fig. 7 a manner ot arranging the circuits in connection With thedesignating contacts ot the line finder is shown in which the line relay, for example ot a calling sul,

scriber also disconnects the battery from the designating contacts 91, 92 as in Fig. 2. The arrangement ot Fig. 7 di'lers trom that ot Fi 2 however in that. the calling line cennected to the bank contact set of the desi entre ing contact 92 that is first reached by the tinder Wipers and the brushes, it they should overstep the designating Contact and only be stopped at the next contact 91, are stopped back by a magnet 93 onto the contact 92.

ln the arrangement shown in Fig. 5 the stopping magnet 19 is not bridged a condenser. but its quick operation is brought about by a resistance 94 bein included inlits energizing circuit as soon as it has attracted its stopping pavl 57.

ln 6 the stopping magnet 19 has tivo coils. The retraction ot the stopping payvl is brought about by the ampere turns of the energizin Winding 95 beine; counteracted by a Cil llt)

winding 96 at the moment in which the brush 97 reaches a designating contact. The counteractingl ampere turns 96 are stronger to a certain degree than the ampere turns 95 but not so strong as to carre the retracted stopping pawl to be attracted again.

In Fig. 32l a group selector is shown which executes long rotary steps in response to numerical impulses instead oitl vertical steps. This is accomplished by means of a cam disk 300. The operation ot the selector will be obvious from the following description of the operations that take place in setting it onto the desired bank contact group.

lVhen a calling party has been connected through to the group selector, Fig. 3, its impulse relay 301 is energized. It also results in Ythe cnergization ot' the release relay 302 (negative pole, 303, 302, resistance 304, positive pole). Assuming that the calling subscriber sends in two numerical Vimpulses so that the arnuiture ot the relay 301 drops back twice, a current impulse will flow at each retraction of the armature from the negative pole through 305, 306, 307, 308, arresting magnet 319, to the positive pole. The magnet 319 pulls the holding pawl 320 away from the toothed wheel 321 and this wheel with the cam disk 300 and the brushes 322, 323, 324, 325 is rotated by the tensioned spring (similar to 14, Fig. 1). As soon as the pawl 320 is disengaged from the tooth of the wheel 321 and this wheel turns through a fraction of the pitch ot the. teeth the cam disk -300 closes the contact 326, 327 so that the magnet 319 receives a current that flows from the negative pole through 327, 326, 307.` 308, 319 to the negative pole. The magnet 319 now remains energized until the spring 326 drops into the next notch 329 of the disk 300 so as to open the contact 327 and cause the pawl 320 to engage with a to'otho the wheel 321. The brushes 322-325 will now have executed one teus step. The next numerical impulse will new recnergize the magnet 319 in a circuit extending from the negative pole through 305, 306,307, 308, 319 to the positive pole. The stopping pawl 310 is again withdrawn trom the toothed wheel 321, the contacts 326, 327 are again closed until the spring 326 drops inte the notch 329 and the holding pawl 320 again engages the wheel 321 and the brushes will then have completed their second long step.

In the interval that ensues after the series ot numerical impulses the changeover relay is deenergized by its being short-circuited at contact 331 so that the contact 332 is closed and the relay 333 is energized by a current flowing from the positive pole through 333, ott-normal contact 334 to the negative pole. The relay 333 by its con tact now connects the magnet 319 to the brush 325. It the brush 325 is now standing I on the bank contact of a free trunk the magnet 319 remains deenergizcd and a current flows through the relay 336 in a circuit that extends from the positive pole through 337, 336, 325, wire 338 to the next selector ahead. The relay 336 thus extends the calling party to the next selector. But if the brush 325 is standingon a busy trunk,that is atrunk Whose test wire is connected by a contact 339 in the `connector to ythe negative pole, the magnet 319 will be energized by a current flowing Vfrom the positive pole through 319, 308, 307, brush 325, contact 339 to the negative pole. The magnet 319 then again withdraws the holding pawl 320 from the wheel 321 and the brushes are rotated by the tension spring until brush 325 reaches a test or designating con-v tact that is not connected with the negative pole and therefore belongs to a free trunk. The holding pawl 320 now drops into the wheel 421 and arrests the brushes on 1the contact set of the free trunk.

W'hen the calling subscriber replaces his receiver the contacts 405, 408 are opened and contacts 340, 341 closed. The magnet 319 is now energized by a current flowing through the orf-normal contact 334', 341, 319 to the posit-ive Ypole and this current continues flowing until the cam -disk 300 presses the cam 42 against the spring 344 and thus opens the ollnormal contact 334. The holding pawl 320 is then released by the magnet 319 and the toothed wheel 321 with the cam disk 300 and the brushes is then arrested by the holding pawl 420 in the normal position illustrated. The rewinding magnet 345 receives impulses that ow from the negative pole through the interrupter 346, Contact 340, 345, contact 347 until thel contact 347 is opened by a cam 348 mounted on the spring box. The spring now being fully rewound the rcwinding magnet 345 is deenergized.

In Fig. 8 the positions of the bank contacts with respect to each other are digrammatically illustrated. From the illustration it ap pears that the designating contacts (as 48, 49) are displaced with respect to the other contacts ofthe contact row so that-the voice current contacts 51', 512 and thecontacts 51 connected to the Yholding wire are opposite to gaps between the contacts 48, 49. The holding pawl of the stopping magnet is adjusted so that it arrests the toothed wheel (e. g. 17, F ig. 2) moved with the brushes in a position in which the contacting ends of thewipers stand in a gap between two designating contacts but in the middle of the associated bank contacts 51, 51', 512. By this adjustment the greatest time of deenergization of the stopping magnet is attained.

Instead of displacing the bank contacts the same result can of course be obtained by displacing the ends of the brushes with respect to each other in a corresponding manner.

In reference to the selector shown in F ig. 1 it is to be mentioned that instead of the ioo groove 29 andthe pin 30 a guide fork 40 placed near the periphery of the wheel 17 and a guide arm 4l projecting Jfrom the shaft l and arranged to slide in the fork 40 may be provided. By this arrangement the play between the shalt l and the wheel 17 can easily be reduced to a traction ot' a millimetre. Y

It is also to be noted that the contact 433 may simply be opened and closed by the stopping pawl 418 instead ot' using` a special cam disk 00 tor this purpose. rlhe cam disk Ll0() could then be dispensed with.

l claim Y Y l. An electromechanically controlledrtelephone system, comprising telephone lines, an impulse producer associated with each line, power driven switches t'or interconnecting said telephone lines, an arresting wheel on each said switch, an arresting pawl on each switch that cooperates with its arresting wheel, an electromagnet ior operating each said pawl to allow the power to-move the switch in steps ot dil'lierent lengths, and means tor energizing' said electromagnets to operate their pawls in response to the impulses produced by said impulse producers.

2. In an electromechanical telephone system, lines, a dial impulse producer in each line, and conversationalswitches having seltcontained power means and brushes adapted to execute steps of diiierent magnitudes in the rhythm of electric impulses produced by said impulse producers.

3. vln an electromechanical telephone system, line `lin ders and connectors having bank contacts and brushes cooperating therewith, lines connected to said bank contacts, electric impulse producers associated with said lines, stopping magnets for stopping the brushes ot said line tinders on bank contacts of calling lines. power means ,tor drivingline tindex.' brushes in a continuous motion until they `ltopped by a stoppingl magnet, stoi'iping magnets 'for said connectors that stop the connector brushes at desired points ot their ill;

contact banks, and power means for movingV the connector brushes in steps ot' different lengths under the control ot their stopping -magnets and in the rhythm ot impulses sent from said impulse'producers.

4;. In an electromechanical telephone system.y line find-.rs and connectors havingl bank contacts and brushes cooperating therewith, lines connected to said bank contacts, electric impulse producers associated with said lines. stopping magnets for stopping the brushes oil said-line iinders, on bank contacts ot calling lines, springs for driving line tinder brushes in a continuous motion until they are stopped bv ra stopping magnet, stopping magnets for said connectors that stop the connector brushes at desired points ot their contact banks, and springs for moving the connector brushes in steps ot different lengths under the control of their stoppingmagnets and in the rhythm ot impulses sent from said impulse producers.

5. A telephone system comprising calling and wanted lines, line tinders and connectors havingbank contacts and brushes that cooper'- ate with said bank contacts, springs for moving the brushes ot a line finder .in ay continuous motion into connection with calling lines? and an electromagnet for stopping the line finder on the calling line.

6. A. telephone system comprising calling and wanted lines, line'linders, group selectors and connectors tor interconnecting calling and wanted lines said .selectors and connectors haring self-contained power means, selecting impulse producers associated with said lines, and electromagnets lor controllingl the movements of said selectors and connectors in steps ot different lengths in the rhythm ot impulses sent from said impulse producers. l

Y. A telephone system comprising calling and wanted lines, switches having pring driven rwipers adapted to execute separate long and short steps for interconnecting calling and wanted lines, and electromagnets tor determining the lengths ot steps executed by said switches in their line-interconnecting operations. f

8. A telephone system comprising calling and wanted lines, switches having spring driven wipers adapted to execute separate long and short' steps for interconnecting calling and wanted lines, electroinagnets tor determining the lengths of steps executed by said switches in their line-interi?onnecting operations, and electric condensers for quickening the action of the armatures of said electroinagnets.

9. A telephone system comprising callingl and wanted lines; trunks; lineiinders. grou selectors and connectors; a spring motor tor n'ioving a line finder in one continuous motion onto a calling line, a spring motor tor moving a group selector stepwise onto a desired group and then in one continuous motion onto a said trunk, and a spring motor for moving a connector stepwise first onto a desired group and then onto thewanted line in the group; and electromagnets for determining` the extents of the switch movements caused by said springs.

l0. A telephone system crunprising calling' and wanted lines; trunks; line linders, group selectors and connectors; a spring motor for moving a line finder in one continuous motion onto a'calling line, a spring motor for moving a group selector stepwise onto a desired group and then in one continuous motion onto a said trunk7 and a spring motor for moving a connector stepwise first onto a desired groiip and then onto the wanted line in the group; electromagnets having armatures for determining the extents of the switch movements caused by said springs, and condensers for' quickening the action of the armatures ofi' said eiectromaonets.

ll. A telephone system comprising calling nel wanted lines, power driven line finders and connectors for interconnecting calling and wanted lines, a brush carrier and toothed wheel in each line finder and con- Hector, an armature normally in engagement with each toothed wheel, and electromagnets 'for raising said arniatures from said toothed wheels to allow the brushes of the line finders and connectors to move onto calling and wanted lines l2. ir telephone system comprising calling and wanted lines, spring driven line finders and connectors for interconnecting calling` and wanted lines, a brush carrier and toothed wheel in each line finder and connector, an armature normally in engagement with each toothed wheel, and electromagnets for raising said armatures from said toothed wheels to allow the brushes of the line finders and connectors to move onto calling and wanted lines under control of the associated springs.

13. A telephone system comprising calling and wanted lines; trunks; power driven line finders, group selectors and Connectors for interconnecting calling and wanted lines; a brush carrier and toothed wheel in each line finder, group selector and connector; an armature normally in engagement with each toothed wheel; and electromagnets for raising said armatures from said toothed wheels to allow the brushes of the line finders, group selectors and connectors to move ont-o calling lines, trunks and wanted lines respectively.

le. A telephone system comprising calling and wanted lines; trunks; spring driven line finders, group selectors and connectors for interconnecting calling and wanted lines; a brrsh carrier and toothed wheel in each line finder, Q'roup selector and connector; an arifiature normally in engagement with each toothed wheel; and electr-:imaginas for raising sail/l armatures from said toothed wheels to allow the brushes ofthe line finders, group selectors and connectors to move onto calling lines, trunks and wanted lines respectively.

A telephone :system con'i'prising ycallif-.ig and wanted linesr` power driven line finders and connectors for interconnecting callingl and wanted il a brush carrier and toothed wl el in each me finder and connector, an ai nature normally in engagement with each toothed wheel, elec romagnets for raising said ariiatures from sail toothed wheels to allow the brushes et the line finders and connectors to move onto calling and wanted lines, and condensers for quickening the dropping movements of said raised armatures.

it?. A telephone system comprising calling and wanted lines; trunks; power driven line finders, group selectors and connectors for interconnecting calling and wanted lines; a. brush carrier and toothed wheel in each line finder, group selector and connector; an armature normally in engagement with each toothed wheel; electromagnets for raising said armatures from said toothed wheels to all-ow the brushes of the line finders, group selectors and connectors to move onto calling lines, trunks and wanted lines respectively, and condensers for quickening the dropping movements ol said raised armatures.

1li'. A telephone system comprising calling and wanted lnes impulse producers; power driven line finders and connectors for interconnecting calling and wanted lines; a brush carrier and toothed wheel in each line finder and connector; an armature normally in engagement with each toothed wheel in each line finder and connector', electromagnets in the line finders for raising the armatures from their toothed wheels to permit the brushes to move onto calling lines; and electromagnets for raising from and lowering onto the toothed wheels of' the connectors the armatures or" the connectors in the rhythm otl the impulses sent trom said impulse producers.

18. A. telephone system comprising calling and wanted lines; impulse producers; spring driven line finders and connectors for interconnecting calling and wanted lines; a brush carrier and toothed wheel in each line finder and connector; an armature normally in engagement with each toothed wheel in each line finder and connector; electromagnets in the line finders for raising ine armatures from their toothed wheels to permit the 1crushes to move onto calling ines; and electromagnetff'; for raising from and lowering onto the toothed wheels of' the connectors the armatures of the connectors in the rhythm of the impulses sent from said impulse producers. i9. il telephone system comprising calling and wanted lines; trunks; impulse producers; power driven line finders, g oup selectors and connectors for interconnecting calling and wanted lines; hrush carrier and toothed wheel in each line finder and group selector; an armature adapted to engage with each toothed wheel in each line finder and group selector; electromagnets in the line finders for moving-r the armatures relatively to then' toothed wneels to permit their brushes to move onto `calling lines; and elcctromagnets in the group selectors for moving the armatures relatively to their toothed wheels to permit their brushes to move onto free trunks.

20. A telephone system comprising callingl and wan ted lines trunks impulse producers; spring driven line finders, group selectors and connectors for interconnecting calling and wanted lines; a brush carrier and toothed wheel in each line finder and group selector; an armature adapted to engage with each toothed wheel in each line finder and group selector; electromagnets in the line finders for moving the armatures relatively to their toothed wheels to `permit the brushes to move Cil onto calling lines; and electromagnets in the group selectors for moving the armatures relatively to their toothed Wheels to permit their brushes to move onto free trunks.

2l. In a line connecting syst-em, two-Wire lines, an impulse producer associated with each line, line relays, a switch comprising bank contacts, a brush carrier, brushes that Wipe over said bank contacts, a self-contained power device for driving said brushes in a continuous motion over any plurality o'l" saidbank contacts, a toothed arresting member on said brush carrier, a starting and stopping member adapted to cooperate with said toothed member for starting and stopping said brushes, an electromagnet 'r'or controlling said starting and stopping member, an electric circuit for energizing said electromagnet, means controlled by current impulses from said impulse producer through a said line and a line relay for closing said circuit to energize said electromagnet and start the continuous motion of said brushes, and means whereby said electron'iagnet is d'eencrgized to cause said member to stop the brushes on any desired individual bank contact.

22. In a line connecting system, twovfire lines, an impulse producer associated with each line, line relays, a switch comprising` bank contacts, a brush carrier, brushes that Wipe over` said bank contacts, a spring for driving said brushes in a continuous motion over any plurality ci' said bank contacts, a toothed arrestingmember on said brush carrier, a starting and stopping member adapted to cooperate with .said toothed member for starting and stopping said brushes, an electromagnet for controlling said starting and stopping member, an electric circuit 'tor energizing said electromagnet, means controlled by current impulses from said impulse producer through a said line and a line relay tor closing said circuit to energize said electromagent and start the continuous motion ol' said brushes, and means whereby said electromagnet is deenergized to cause'said member to stop the brushes on any desired individual bank contact.

23. In a line connecting system, two-Wire lines, animpulse producerassociated with said line, line relays, a switch comprising bank contacts, a brush carrier, brushes that wipe over said bank contacts, a spring 'for driving said brushes in a continuons motion over any plurality of said bank contacts, a toothed arresting member on said brush carriers, a starting and stopping member adapted to cooperate with said toothed member for starting and stopping said brushes, an electromagnet tor controlling said starting and stopping member, an electric circuit for energizing said electromagnet, means controlled by current impulses from said impulse producer through a saidline and a line relay for closing said circuit to energize said electroinagnet and start the continuous motion ot' said brushes, means whereby said electromagnet is deenergized to cause said member to stop the brushes on any desired individual bank contact,rand means for retensioning said spring a't'ter cach use oi'f same.

24. In a high-speed telephone system, calling lines, called lines, trunk lines leading lrom said calling lines toward said calling lines, a plurality olf bank contacts in which said trunk lines terminate, a circuit controlling brush adapted to Wipe over said contacts, a sha'lit to which said brush is attached, a toothed wheel for said shaft, a stopping paivl for said Wheel, a magnet ior controlling said pavvl, means controlled by a calling line for energizing said magnet to allow said brush to be moved, means for designating one Ot said bank contacts, means responsive to the movement ot said brush from a non-designated preceding contact to a succeeding designated contact, tor causing said magnet to be deenergized, means responsive to the deenergization of said magnet :tor causing said paWl to rapidly engage said toothed Wheel, and a condenser for` accelerating the deenergization ot said magnet.

25. In a high-speed telephone system according to claim 2d in which the accelerating condenser is connect-ed in parallel With the controlling magnet. i

26. In a telephone system, a plurality ot telephone lines, a plurality of bank contacts in which said lines terminate, a set of spring driven brushes, a toothed Wheel and cooperating detent for positively arresting said brushes when they reach a designated set of contacts, and circuit arrangements controlled over said lines tor causing said switch to act as a telephone line selector.

27. In telephone system, a plurality oi" telephone lines, a plurality of bank contacts in which said lines terminate, a set ot' spring driven brushes, a toothed Wheel and cooperating detent 'for positively arresting' said brushes When they reach a designated set of contacts, and circuit arrangements controlled over said lines 'for causing said switch to act as a group selector.

In testimony Whereo'l l have affixed my signature.

FRITZ LDENDORFF. 

